GREENBELT, Md. (WUSA9) -- A D.C. man has pleaded guilty to charges stemming from a carjacking at the Largo Metro station in 2011.

Department of Justice officials say 23-year-old Samuel Damien Bynum pleaded guilty on Friday to conspiring to use a gun during a carjacking, using a gun during a carjacking, carjacking and being a felon in possession of a gun and ammunition.

According to his plea agreement, in January 2011, Bynum and others conspired to commit armed carjackings in Prince George's and Montgomery counties.

We're told on May 25, 2011, Bynum and his co-conspirators drove to the Largo Metro station in a car they had stolen during a carjacking at the New Carrollton Metro station a few days earlier. Bynum saw two people park their car in the garage and followed them into the stairwell. Bynum later told officers that he blocked the stairs so that his co-conspirators, who carried handguns, could rob the couple. One of the suspects hit one of the victims with a handgun, but they weren't able to take the victim's car keys. Bynum and his conspirators fled, but returned later to steal the car after finding the keys during their flight.

A co-conspirator gave Bynum a gun and told him to start shooting if the victims did anything. When a victim tried to get into the car, Bynum and his conspirators shot several times at both victims. One victim suffered a permanent injury that required significant and ongoing medical attention, accoridng to officials.

Authorities say Bynum had bought the handgun he used in the carjacking. He was previously convicted of a felony and was prohibited from possessing a gun and ammunition.

Bynum faces a mandatory minimum sentence of 10 years and a maximum sentence of life in prison when he is sentenced on May 6.

Two alleged co-conspirators have been charged in federal court and another was prosecuted in state court.